I recently picked up a couple of unpopulated and unused Twiggy analog and digital boards (from John W.). Interestingly, the digital board has a 1985 revision in the PCB.
Apple part number 853-0102 copyright 1982.
PCB obverse marked 820-0051-C copyright 1982.
PCB reverse marked 820-0051-C copyright 1985.
(https://i.imgur.com/QpBS5il.png)
(https://i.imgur.com/dl2IQzs.png)
Did Apple really make a revision to the digital board more than a year after it was discontinued?
Edit: No. All evidence indicates this was simply a typo in 1982 during the development of digital board revision C, or possibly during a post-Apple recreation of this revision C board.
Just for posterity, here's a scan of the analog board also. It seems to be the older (?) and simpler revision that has "TWIGGY ANALOG BOARD" printed on the PCB, part number 820825A.
(https://i.imgur.com/KoeoAby.png)
(https://i.imgur.com/uSV6lSq.png)
My working Twiggy drives do not feature that revision. Mine are the same, more complex configuration as this one, pictured below - borrowed from RR Auction (Del Yocam's machine). Does anyone know the story of why the analog board went through such a dramatic change?
(https://i.imgur.com/Uv6GAZU.jpeg)
Here's another one of the older (?) and simpler analog boards, shown below. This example is fully populated, marked 820825B and additionally reads SK T010-01. Seems to be a close relative to the bare board that John sent.
(https://i.imgur.com/2k14nr4.jpeg)
(https://i.imgur.com/A8TxXOP.jpeg)
Quote from: ried on March 31, 2025, 07:24:04 PM
My working Twiggy drives do not feature that revision.
Strangely enough, my set has one of each. Both are marked as Rev F.
Quote
... more complex configuration
Does anyone know the story of why the analog board went through such a dramatic change?
AFAICT, they are the same circuit, the board layout was re-done. Comparing their styles, I suspect the less spread-out version was at the prototype stage, and only when the design was finalized was the board laid out again with the Apple logo and more detailed ground fill. I do wonder if there is any difference in performance and if the new layout was intended to address a known problem that contributed to the poor performance of the Twiggy.
A wild guess is the "1985" designation on the digital board is an error on the reproduction as the copper on the top side says 1982, and it is easy to be confused by looking at a backwards 2 in the x-ray view. One of my boards is 1982 in copper (on both sides), the other 1983 in copper (on both sides), with matching years on the silkscreen. Both are Rev H.
I see one of the older analog boards pictured is "E"; we don't yet have an accurate schematic history of the Twiggy analog board, are there more pics of that particular board?
Along those lines, are all of your Twiggy analog boards marked as Rev "F"?
Quote from: sigma7 on April 02, 2025, 03:10:40 PM
I see one of the older analog boards pictured is "E"; we don't yet have an accurate schematic history of the Twiggy analog board, are there more pics of that particular board?
Along those lines, are all of your Twiggy analog boards marked as Rev "F"?
Here are a few more pictures of the "E" board: https://imgur.com/a/8xiL1I9
My working drives do indeed feature Rev "F" analog boards.
There's a set of Twiggy drives for sale on Facebook Marketplace. I believe you have to be a member of the "Apple Vintage Marketplace" group to see the ad, but here's the link:
https://www.facebook.com/commerce/listing/1151219836747439?media_id=0&ref=share_attachment
Looks like one complete set of Twiggy drives with the Rev. F analog boards, as well as a set of two parts drives - one missing an analog board, and another with a Rev. E analog board.
Quote from: ried on April 11, 2025, 10:55:29 PM
There's a set of Twiggy drives for sale on Facebook Marketplace. I believe you have to be a member...
For those of us not utilizing Facebook currently (and for future reference since historical items on Facebook can be hard to find I'm told), please save / upload screendumps or whatever to the extent allowed by the terms of service.
And perhaps suggest to the seller that they post here! ... Or provide permission for you to repost.
Sure, here's a copy of the images from the ad: https://imgur.com/a/HGDQcJl
I'm absolutely in the camp of "Interested, but don't have Facebook." Been wanting to switch my 2/5 B08B serial back to the Lisa 1 it started life out as.
Quote from: ried on April 11, 2025, 10:55:29 PM
a set of Twiggy drives for sale on Facebook Marketplace (https://www.facebook.com/commerce/listing/1151219836747439?media_id=0&ref=share_attachment)
Wondering ... what is/was the asking price, and where are/were they located?
They're asking $40K and it looks like they're in Aptos, CA.
RR Auction recently sold a set of spare parts Twiggy digital boards, and their images provide an easy way to compare the C, D, and E revisions of the PCB layout. The unpopulated board at the top of this thread is 820-0051-C, and it seems to have been made with a copyright 1985
typo. I don't know if that typo is present on any boards that shipped from Apple, as it may have been caught during the production process - or reproduction process, as the case may be.
Quote from: ried on March 31, 2025, 06:58:32 PMI recently picked up a couple of unpopulated and unused Twiggy analog and digital boards (from John W.). Interestingly, the digital board has a 1985 revision in the PCB.
820-0051-C copyright 1985.
(https://i.imgur.com/dl2IQzs.png)
820-0051-D copyright 1982
(https://i.imgur.com/IlgOUDD.jpeg)
820-0051-E copyright 1983
(https://i.imgur.com/HiZGXYe.jpeg)
Quote from: ried on April 11, 2025, 10:55:29 PMThere's a set of Twiggy drives for sale on Facebook Marketplace. I believe you have to be a member of the "Apple Vintage Marketplace" group to see the ad, but here's the link:
Is the listing still up? I'm a member of that group, but the link you provided just takes me to a blank page for some reason.
That listing is over a year old and was deleted quite a while ago. Images from the listing are still preserved here, however: https://imgur.com/a/apple-lisa-twiggy-drives-HGDQcJl
Oh sorry, I'm stupid and didn't read the dates on your post. I thought this was a new thing!
There's a set on eBay right now...
https://www.ebay.com/itm/156928557708?_skw=apple+twiggy+drives&itmmeta=01M0T3JXRX4FBYE44AG2Z79SMA&hash=item2489abc28c:g:~U0AAOSwpZJoDCXF&itmprp=enc%3AAQALAAAA0GfYFPkwiKCW4ZNSs2u11xD1lrDV6e%2B%2Fh5qqXyG3Xo%2BUyd0blZPJJj9c8Sxg0iBViKkuL9vF3AjRuYLe2x29o8Lrioylmsqm05gdN2IGuamMEm20MAreSZOIoSX7z%2BYTMFnm%2BT0goUmJkLbrVrUfN58y6bJ63hTflK9rmdlsfVNrl%2BFPXUQQVujd0JxIIJVntP2xofX6u1OzsnacouvmrLN8sV5eutIw7sHG%2FxWhgsFCTZGXJq9MzppMyuY1oEqF9D8%2FdYYXCiDmgmbnS1A%2FkS8%3D%7Ctkp%3ABk9SR9Lcy8OGaA
Quote from: Lisa1 on August 24, 2026, 09:43:40 AMThere's a set on eBay right now...
https://www.ebay.com/itm/156928557708?_skw=apple+twiggy+drives&itmmeta=01M0T3JXRX4FBYE44AG2Z79SMA&hash=item2489abc28c:g:~U0AAOSwpZJoDCXF&itmprp=enc%3AAQALAAAA0GfYFPkwiKCW4ZNSs2u11xD1lrDV6e%2B%2Fh5qqXyG3Xo%2BUyd0blZPJJj9c8Sxg0iBViKkuL9vF3AjRuYLe2x29o8Lrioylmsqm05gdN2IGuamMEm20MAreSZOIoSX7z%2BYTMFnm%2BT0goUmJkLbrVrUfN58y6bJ63hTflK9rmdlsfVNrl%2BFPXUQQVujd0JxIIJVntP2xofX6u1OzsnacouvmrLN8sV5eutIw7sHG%2FxWhgsFCTZGXJq9MzppMyuY1oEqF9D8%2FdYYXCiDmgmbnS1A%2FkS8%3D%7Ctkp%3ABk9SR9Lcy8OGaA
If only I could afford them! Maybe someday...